Arcing tip for oil switches



July 19, 1932. .1. N. KELMAN ARCING TIP FOR OIL SWITCHES Filed Feb. l, 1928 2 SheGtS-Sheei l [M504 ,4 rae HTToeA/Ex July 19, 1932- J. N. KELMAN 1,867,848

ARCING TIP'FOR OIL SWITCHES Filed Feb. l, 1928 2 Sheets-Sheet 2 Patented July 19, 1932 UNITED PATENT oralesN JOSEPH N. KELMAN, OF LOS ANGELES, CALIFORNIA, ASSIG-NOR'TO KELMAN V FLFiCVJJIIEtlJ 8a MANUFACTURING COMPANY, OF LOS ANGELES, CALIFORNIA, A CORPORALION OF CALIFORNIA .ARCING TIP FOR OIL SVIITCHES Application filed February 1, 1.928. Serial No. 251,162.

My invention relates to switches, and more particularly to a novel form of arcing tip switch.

The opening and closing of electrical circuits carrying high potential currents of large magnitude present problems of how best to quench the arc that is invariably formed as the circuit through the switch is opened, and how to keep this arc from burning the contacts of the switch. Most high-potential switching is accomplished by means of heavy switches operating submerged in oil of high dielectric strength. This oil quenches any arc which may be formed before these arcs are drawn out far enough to bridge the switch terminals when in an open position. Such an oil will, however, not eliminate arcing, but will simply limit the degree to which it takes place. Arcing invariably occurs, and when large high potential current circuits are broken, the contacts of the switch are burned.

To eliminate the burning of the main contacts of the switch, the arcing tip switch has been devised. These ,switches have a pair of auxiliary contacts which are in engagement to complete the circuit through the switch until after the main switch contacts have been opened, thus eliminating any arcing between the main contacts. The actual arcing takes place between the auxiliary contacts, and these auxiliary contacts are cheaply and easily replaced when they become badly burned.

I have invented a novel type of switch of the arcing-tip type which is Vextremely rugged and very eiiicient.

It is an object of my invention to provide a rugged and efficient arcing tip switch in which the burning of the arcing contacts is reduced to a minimum.

My invention provides an arcing tip member which is pivoted to the stationary structure of the switch, this arcing tip member being spring actuated.

It is an object of my invention to provide an arcing tip which is spring actuated and pivoted to the stationary structure of the switch.

A further object of my invention is to provide an arcing tip switch in which the contacts may be easily replaced. i

Further objects and advantages of my invention will be made evident hereinafter.

Referring to the drawings,-

Fig. 1 is a utility view showing an oil switch equipped with the arcing tips of Vmy invention.

Fig. 2 is an enlarged sectional view through one-terminal of the switch shownin Fig. 1.

Fig. 3 is a vertical sectional view taken on the line 3-3 of Fig. 2.

' Fig't is a horizontal sectional view Vtaken on the line i- 4; of Fig. 2. f

Referring particularly to Fig. 1,v the switch of my'invention is enclos-ed in a shell 10comprising a cylindrical member l1 closed at its lower end by a lower plate 12 and at its upper end by an upper plate 13. Mounted on a supporting structure 15 in the shell 10 are outer insulators 16 and 17. Secured to the upper end of each of the outer insulators is a contact support 18 which has a main switch contact 20 secured thereto.

As best shown in'Fig. 4, each mainV contact 2O comprises U-shaped plates 21 having inner legs 22. The U-shaped plates 21 are secured to the contact support 18 by means of suitable rivets or bolts 24. f Y

Adapted to snugly fit between each pair of inner legs 22 are blades 25, these blades having a lower portion 26ZL extending below the main switch contacts 20 when the blade is in engagement therewith. The blades 25 are actuated by a pantograph mechanism 26. This pantograph mechanism ismounted on a central insulator 27 secured to the support 15, this insulator supporting a tubular member 29 which allows a plunger 30 to bev vertically movable therein. The upper end of the 'plunger 30 is connected to an upper connector plate 32, this plate being also pivotally connected to the inner ends of each blade 25 by meansof pins 33, as best illustrated in Fig. 1. A lower connector plate 35 isl secured to the lower end of the tubular member 29, this connector plate being pivotally connected to a pair of links 37 by means of pins 38. The outer end of each link 37 is pivotally connected to its respective blade 25 by means of pins 39. l

The pantograph 26 is adapted to be operated by means of a connecting rod 42 which is pivotally connected to the upper connector plate 32, as indicated by the numeral 43. The upper end of the connecting rod 42 is pivotally connected to a rocker arm 45 which is connected to a rod 46 pivoted in the shell 10. Secured to the rod 46 outside the shell is a lever 47, this lever being connected by a link 48 to a suitable actuating mechanism indicated by the numeral 49, this actuating mechanism being adapted to open and close the switch of my invention by actuating the pantograph mechanism in a manner to be described.

Extending upward from each contact support 18 is an arm 52. The upper end of the arm 52 is bifurcated, as indicated at 53, to form ears 54 extending from the upper end of the arm 52. A pin 55 extends between the ears 54. Pivotally connected to this pin is an arcing-tip structure 58, this structure comprising a pair of legs 59, one of which extends on each side of the main contact 20. Extending between the legs 59 respectively above and y below the main contact 20 are upper and lower cross members 62 and 63. Secured to the lower cross member 63 by bolts 64 is a primary arcing contact 65 having a plane surface 66 thereon. This primary arcing contact 65 is adapted to be engaged by a secondary arcing contact 67 having a plane surface 67, this secondary arcing contact 67 being rigidly mounted to the lower portion 26a of the blade 25 by suitable screws, not illustrated. The primary and secondary arcing contacts 65 and 67 comprise auxiliary contacts which maintain the circuit through the switch until after the blade 25 has disengaged the main contacts 20. These arcing contacts 65 and 67 may be made of copper, carbon, or other suitable materials, and these tips may be easily replaced by simplyremoving the screws holding these tips to their respective supports.

Secured by screws 70 to the upper end of the arm 52, just below the ears 54, is a plurality of flat springs 71, these springs being bent downward and attached to the upper cross member 62 by means of screws 72. The Hat springs 71 thus exert a force on the arcing tip structure 58 which tends to move this structure in a counter-clockwise direction. The maximum position of the arcing-tip structure 58 is determined by a stop member 76 extending between the legs 59, this stop member coming into contact with the arm 52 when the arcing-tip structure 58 reaches a position indicated by the dotted lines 78 of Figs. 1 and 2.

The arm 52 and the upper cross member 62 are electrically connected through a flexible conductor 8O extending parallel with the springs 71 and held in place by the screws 7 0 and 72. This flexible conductor is preferably of the woven or stranded types wellknown in the art.

Secured to each contact support 18 by bolts is a terminal 91 adapted to receive a heavy conductor 92. The upper end of each conductor 92 extends through a suitable insulator 94 secured in the upper plate 13 of the shell 10.

The operation of my device is as follows: l

The shell 10 is filled with o-il to a level indicated by the numeral 95 of Fig. 1. The upper ends of the conductors 92 are inserted in a high potential circuit adapted to be broken by means of the switch of my invention. lVhen the mechanism is in its full line position indicated in Fig. 1, the switch is closed and current may How through one conductor 92 to its attached main contact 20. The main contacts 20 are bridged by the lades 25 of the pantograph 26 so that current flows through this pantograph to the opposite main contact, whence it may return to the line through the conductor 92. When it is desired to open the circuit, the actuating mechanism 49 is operated so as to draw the lever 47 downward. As this movement starts, the blades 25 are withdrawn from the main contacts 20 through a position indicated by dotted lines 97. As this movement occurs, the primary arcing contacts 63 follow the secondary arcing contacts 67 as these secondary contacts move inward. A firm contact between the primary and secondary arcing contacts 65 and 67 is insured by the springs 71. Then the arcing-tip structure 58 reaches its position shown by dotted lines 78, the stop members 76 engage the arms 52, thus preventing any further counter-clockwise rotation of the arcing-tip structure 58. As indicated in Fig. 2, this condition occurs `just after the blades 25 have been disengaged from the main contacts. At this instant, the current, previously passing from the main contacts 2O to the blades 25, is transferred through the flexible conductor 89 to the-arcing-tip struct-ure 58 so that this current passes through the primary and secondary arcing f contacts 65 and 67. Thus, no arcing will occur between the blades 25 and the main contacts 20, inasmuch as a parallel path has been established over which the current may travel.

As the blades 25 move inward due to a further rising of the upper connector plate 32 of the pantograph 26, the circuit between the primary and secondary arcing contacts 65 and 67 is broken, and arcing will occur between these contacts, this arcing being quenched by the oil in the shell 10. As the upper connector plate 32 moves still vfurther upward, the blades 25 are drawn into a position indicated by dotted lines 99 of Fig. 1, this pantograph action being wellknown in the art. As soon as the arcing between the arcing contacts 65 and 67 is quenched, the circuit through the switch is broken.

Any arc that is formed is quickly quenched by the oil, and I have found that the arcing contacts are not seriously burned with continued operation of the switch. Should the switch be operated under excessive overloads, it may be necessary to replace the arcing contacts. This is easily accomplished by removing the bolts and screws securing the contacts in place and attaching new contacts and 67.

It is well-known that if the link 4:8 be lowered at a constant rate, the speed of the. lower portions 26a of the blades 25 will increase as the pantograph mechanism moves toward its dotted line position indicated by the numeral 99. It follows directly that these lower portions 26 will be moving at a greater speed when in the dotted line position 97 than when in the full line position shown in Figs. l and 2. Thus, the arc formed between the arcing contacts 65 and 67 is quickly broken, due to the peculiar arrangement of the arcingstip structure and the pantograph mechanism.

I claim as my invention:

l. In an electrical switch, the combination of: a contact support; a main contact on said contact support; a movable blade; means adapted to actuate said blade to make and break contact with said main contact; an arm on said contact support; legs pivoted to said arm, said legs extending to either side of said main contact; upper and lower cross members holding said legs in spaced relationship; a plate spring acting between said upper cross member and said arm; a primary arcing contact carried by said lower cross member; a secondary arcing contact by said blade; a sto; -member carried by said legs, said stop member engaging said arm to separate said primary and said secondary arcing contacts after said blade has been disengaged from said main contact; and a iexible consaid blade before the disengagement of said primary and said secondary arcing contacts; and a flexible conductor connecting said arm and said upper cross member.

3. In an electrical switch, the combination of: a contact support; a main contact on said contact support; a movable blade; pantograph mechanism adapted to actuate said blade to make and break contact with said main contact; an arm on said contact support; legs pivoted to said arm, said legs ex. tending to either side of said main contact; upper and lower cross members holding said legs in spaced relationship; a plate spring acting between said upper cross member and said arm; a primary arcing contact carried by said lower cross member; a secondary arcing contact carried vby said blade; a stopmember carried by said legs, said stop-member engaging said arm to separate said primary and said secondary arcing contacts after said blade has been disengaged from said main contact, said pantograph mechanism also being adapted to move said blade comparatively slowly during contact of said main contact with said blade and to increase the speed of said blade before the disengagement of said primary and said secondary arcing contacts; and a flexible conductor connecting said arm and said upper cross member.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 27th day of January, 1928.

JOSEPH N. KELMAN.

ductor connecting said arm and said upper cross member.

2. In an electrical switch, the combination of: a contact support; a main contact on said contact support; a movable blade; means adapted to actuate said blade to make and break contact with said main contact; an arm on said Contact support; legs pivoted to said arm, said legs extending to either side of said main contact; upper and lower cross members holding said legs in spaced relationship; a

plate spring acting between said upper cross member and said arm; a primary arcing contact carried by said lower cross member; a secondary arcing contact carried by said blade; a stop-member carried by said legs, said stop-member engaging said arm to sepal rate said primary and said secondary arcing contacts after said blade has been disengaged from said main contact, said means also being adapted to move said blade comparatively slowly during contact of said main contact with said blade and to increase the speed of CERTIFICATE OF CGRRECTEON.

Parent No. 1,867,848. Saly 19, 1932.

JOSEPH N. KELMAN.

It is hereby certified that error appears in rhe printed specification of the abeve numbered patent requiring correctinu as fsllows: Page 3, line 37, claim 1, after "cuntat" insert the Word carried; and hat the said rtsrs Patent shculd he read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 1st day of November, A. D. @32.

J. Moore, (Seal) Acting Commssioner of Patents.

CERTIFICATE OF CORRECTON.

Patent No. 1,867,848. July 19, 1932.

JOSEPH N. KELMAN.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as fellows: Page 3, line 37, claim i, zitter "contact" insert the word carried; anti that the said etters Patent siieuiti be read with this correction therein that the same may conform to the reeerd et the case in the Patent Office.

Signed and sealed this 1st day of November, A. i932.

3. Moore, (Seal) Acting Cemmissioeer of Patents. 

